Rosetta’s Philae lander is scheduled to descend to the comet’s surface this coming November. The effect of the comet’s unusual shape on the landing cannot be estimated yet.

Compositional difference?

The fact that two clearly distinguishable parts make up Churyumov-Gerasimenko is a surprise.

“The two blocks likely formed 4.5 billion years ago, collided at low speed, stuck to each other and have since been moving together,” says Kührt. “Scientifically, it is now of course very interesting to find out whether the two components differ in their composition.”

Indeed, if the two parts are from different regions, their structure might also differ.

Looking for a landing spot

“For the landing, it is especially important to have a detailed view of the comet and understand how the two parts are connected,” says Koen Geurts, an engineer at the Lander Control Centre at DLR in Cologne.

“So far, it looks as though there are large flat regions on the comet,” Geurts said in a DLR press statement.

The lander needs to touchdown on a reasonably flat terrain. Furthermore, the landing site should also have a day-night cycle so that the Philae lander can cool down out of the sunlight and so that scientific research can be carried out under different conditions.

Lastly, regular communication with the Rosetta spacecraft is necessary for the lander team to send the recorded data to Earth and empty the data storage. “These aspects are currently still hard to assess,” Geurts said.

NOTE:Take a look at this impressive movie made by combining and interpolated 36 images that were acquired by the OSIRIS camera on July 14th at intervals of 20 minutes, clearly showing that the comet consists of two interconnected parts.